Catalyst-Free Crosslinking Modification of Nata-de-Coco-Based Bacterial Cellulose Nanofibres Using Citric Acid for Biomedical Applications

Bacterial cellulose (BC) has gained attention among researchers in materials science and bio-medicine due to its fascinating properties. However, BC’s fibre collapse phenomenon (i.e., its inability to reabsorb water after dehydration) is one of the drawbacks that limit its potential. To overcome this, a catalyst-free thermal crosslinking reaction was employed to modify BC using citric acid (CA) without compromising its biocompatibility. FTIR, XRD, SEM/EDX, TGA, and tensile analysis were carried out to evaluate the properties of the modified BC (MBC). The results confirm the fibre crosslinking phenomenon and the improvement of some properties that could be advantageous for various applications. The modified nanofibre displayed an improved crystallinity and thermal stability with increased water absorption/swelling and tensile modulus. The MBC reported here can be used for wound dressings and tissue scaffolding.

Effective removal of tetracycline antibiotics from wastewater using practically applicable iron(III)-loaded cellulose nanofibres

The non-toxic and completely biodegradable cellulose within bamboo is one of the most abundant agricultural polysaccharide wastes worldwide, and can be processed into cellulose nanofibres (CNFs). Iron(III)-loaded CNFs (Fe(III)@CNFs) derived from bamboo were prepared to improve the adsorption of tetracycline (TC), chlortetracycline (CTC) and oxytetracycline (OTC) from an aqueous solution. The preparation conditions of Fe(III)@CNFs suitable for the simultaneous adsorption of three tetracycline antibiotics (TCs) were investigated. Various analyses proved the abundance of oxygen-containing functional groups and the existence of Fe(III) active metal sites in Fe(III)@CNFs. In batch experiments, Fe(III)@CNFs were applied under a wide pH range and the maximum adsorption capacities were 294.12, 232.56 and 500.00 mg g −1 (for TC, CTC and OTC, respectively). In addition, different concentrations and types of coexisting anions have a weak effect on TCs adsorption. The original TCs adsorption capacities of Fe(III)@CNFs remained stable (greater than 92%) after five cycles when UV + H 2 O 2 was used as the regeneration method. Four adsorption mechanisms (surface complexation, hydrogen bonding, electrostatic interaction and van der Waals force) were obtained for the endothermic adsorption of TCs, among which surface complexation between Fe(III) and TCs always dominates. The practically applicable Fe(III)@CNFs adsorbents are promising for TCs enrichment and remediation in engineering applications.

3D Collagen-Nanocellulose Matrices Model the Tumour Microenvironment of Pancreatic Cancer

Three-dimensional (3D) cancer models are invaluable tools designed to study tumour biology and new treatments. Pancreatic ductal adenocarcinoma (PDAC), one of the deadliest types of cancer, has been progressively explored with bioengineered 3D approaches by deconstructing elements of its tumour microenvironment. Here, we investigated the suitability of collagen-nanocellulose hydrogels to mimic the extracellular matrix of PDAC and to promote the formation of tumour spheroids and multicellular 3D cultures with stromal cells. Blending of type I collagen fibrils and cellulose nanofibres formed a matrix of controllable stiffness, which resembled the lower profile of pancreatic tumour tissues. Collagen-nanocellulose hydrogels supported the growth of tumour spheroids and multicellular 3D cultures, with increased metabolic activity and matrix stiffness. To validate our 3D cancer model, we tested the individual and combined effects of the anti-cancer compound triptolide and the chemotherapeutics gemcitabine and paclitaxel, resulting in differential cell responses. Our blended 3D matrices with tuneable mechanical properties consistently maintain the growth of PDAC cells and its cellular microenvironment and allow the screening of anti-cancer treatments.

Design and Development of Cellulosic Bionanocomposites from Forestry Waste Residues for 3D Printing Applications

This paper deals with the development of cellulose nanofibres (CNFs) reinforced biopolymers for use in packaging applications. Cellulose nanofibres were extracted from sawdust by a combination of chemical and mechanical treatments. The extracted cellulose nanofibres were chemically modified (fCNFs) and characterised by Fourier Transform Infrared Spectroscopy (FTIR). Bionanocomposites were prepared from biopolymers polylactic acid/polybutylene succinate (PLA/PBS) and cellulose nanofibres by compounding in a twin-screw extruder followed by injection moulding. The developed bionanocomposites were subjected to mechanical and thermal characterisation. As part of product development, CNF-biopolymer pellets were also extruded into filaments which were then 3D printed into prototypes. This work is a successful demonstration of conversion of waste residues into value-added products, which is aligned to the principles of circular economy and sustainable development.

Fabrication of Paper Sheets Coatings Based on Chitosan/Bacterial Nanocellulose/ZnO With Enhanced Antibacterial and Mechanical Properties

Here, we designed the composition of the coating of the paper sheets composed of chitosan, bacterial cellulose (nanofibres), and ZnO with boosted antibacterial and mechanical activity. We investigated the compositions with ZnO exhibiting two different sizes/shapes: (1) rods and (2) irregular sphere-like particles. The proposed processing of bacterial cellulose resulted in the formation of nanofibers. Antimicrobial behavior was tested using E. coli ATCC® 25922™ following ASTM E2149-13a standard. Mechanical properties of the paper sheets were measured by comparison of tearing resistance, tensile strength, and bursting strength according to ISO 5270 standard. The increased antibacterial response is assigned to the combination of chitosan and ZnO (independently of its shape and size), while the boosted mechanical behavior is due to bacterial cellulose nanofibers. Therefore, the proposed composition is an interesting multifunctional mixture for coatings in food packaging applications.

Comparative Life Cycle Assessment of Cellulose Nanofibres Production Routes from Virgin and Recycled Raw Materials

Nanocellulose-based materials are attracting an increasing interest for the positive role they could play in sustainable development; being originated from renewable resources. Moreover, cellulose has a high potential of recycling from both post-consumer waste and industrial waste. Both factors, i.e., recyclability and renewable resources; results are also extremely favourable in the perspective of circular economy. Despite all these positive aspects, an industrial production has yet to start. At the lab scale, many preparation methods of cellulose nanofibres (CNF) are available; here, the three most common are analysed: (1) enzymatic pre-treatment followed by homogenisation (ENZHO), (2) oxidative pre-treatment combined with homogenisation (TOHO) or (3) oxidative pre-treatment followed by sonication (TOSO). All three processes have been experimentally carried out starting from both virgin and recycled cellulose from industrial waste sludge. The environmental sustainability of these three routes is estimated by the Life Cycle Assessment (LCA) using experimental lab scale data. In this scenario, the comparative LCA has pointed out a superior performance of the ENZHO process, followed by TOHO and, lastly, by TOSO. The influence of energy consumption on the final results has been further investigated by a sensitivity analysis, showing that the TOHO and TOSO routes could reach similar performances by scaling-up the process from the laboratory. The different typology of CNF obtained by conducting the ENZHO process with respect to the TEMPO-mediated oxidation approach is also outlined as an additional element to be considered for the final selection of a suitable process.